Synthesis and Sulfur Oxygenation of a (N<sub>3</sub>S)Ni Complex Related to Nickel-Containing Superoxide Dismutase

Mullins, Christopher S.; Grapperhaus, Craig A.; Frye, Brian C.; Wood, Larry H.; Hay, Amy J.; Buchanan, Robert M.; Mashuta, Mark S.

doi:10.1021/ic901246w

Cited by 39 publications

(32 citation statements)

References 29 publications

(73 reference statements)

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“…Increasing the energy of the HOMO via an increase in Ni-S covalency in (Ni II (L1)) 2− ( 2 ) effectively activates this species towards electrophiles relative to (Ni II (HL2)) − ( 3 ). These results are consistent with previously reported Ni-SOD model compounds containing mixed amine/amidate Ni II N 2 S 2 coordination that are also air-stable 37,38…”

Section: Discussionsupporting

confidence: 93%

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Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Mathrubootham¹,

Thomas²,

Staples³

et al. 2010

Inorg. Chem.

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The distal nickel site of acetyl-CoA synthase (Ni d -ACS) and reduced nickel superoxide dismutase (Ni-SOD) display similar square-planar Ni II N 2 S 2 coordination environments. One difference between these two sites, however, is that the nickel ion in Ni-SOD contains a mixed amine/amidate coordination motif while the Ni d site in Ni-ACS contains a bisamidate coordination motif. To provide insight into the consequences of the different coordination environments on the properties of the Ni ions, we systematically examined two square-planar Ni II N 2 S 2 complexes, one with bisthiolate-glycinamide] and another with bisthiolate-amine/amidate ligation K(Ni(HL2)) (3) [H 4 L2 = N-(2"-mercaptoethyl)-2-((2'-mercaptoethyl)amino)acetamide]. Although these two complexes differ only by a single amine vs. amidate ligand, the chemical properties of them are quite different. The stronger in-plane ligand field in the bisamidate complex (Ni II (L1)) 2− (2) results in an increase in the energies of the d → d transitions and a considerably more negative oxidation potential. Furthermore, while the bisamidate complex (Ni II (L1)) 2− (2) readily forms a trinuclear species (Et 4 N) 2 ({Ni(L1)} 2 Ni) ·H 2 O (1) and reacts rapidly with O 2 , presumably via sulfoxidation, the mixed amine/amidate complex (Ni II (HL2)) − (3) remains monomeric and is stable for days in air. Interestingly, the Ni III species of the bisamidate complex formed by chemical oxidation with I 2 can be detected by electron paramagnetic resonance (EPR) spectroscopy while the mixed amine/amidate complex immediately decomposes upon oxidation. In order to explain these experimentally observed properties, we performed S K-edge X-ray absorption spectroscopy and low-temperature (77 K) electronic absorption measurements as well as both hybrid density functional theory (hybrid-DFT) and spectroscopy oriented configuration interaction (SORCI) calculations. These studies demonstrate that the highest occupied molecular orbital (HOMO) of the bisamidate complex (Ni II (L1)) 2− (2) has more Ni character and is significantly destabilized relative to the mixed amine/amidate complex (Ni II (HL2)) − (3) by ~6.2 kcal mol −1 . The consequence of this destabilization is manifested in the

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Section: Discussionsupporting

confidence: 93%

“…Relatively few examples of mixed amine/amidate nickel complexes have been reported as models for Ni-SOD 34–38. Both Shearer34 and others35 have synthesized nickel-peptide complexes as functional models of Ni-SOD.…”

Section: Introductionmentioning

confidence: 99%

Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Mathrubootham¹,

Thomas²,

Staples³

et al. 2010

Inorg. Chem.

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“…Questions concerning the enzyme's unusual N/S coordination sphere, particularly its stability toward O 2 and reactive oxygen species (ROS), in light of the reactive Ni–S(Cys) bonds, 13 and the catalytic mechanism have prompted researchers to develop maquette-based, 14–20 tripeptide, 21–24 and low molecular weight 25–38 analogues that seek to replicate NiSOD's structure and/or function. 39,40 Indeed, several experimental and theoretical efforts have suggested that the mixed peptide-N/amine-N ligation serves as one key factor to promote greater Ni-character in the redox-active molecular orbital of NiSOD, in particular for the Ni(II) or NiSOD red state, thus preventing unwanted S-oxidation/oxygenation.…”

Section: Introductionmentioning

confidence: 99%

Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N₂S₂ Synthetic Models of NiSOD

et al. 2015

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Superoxide dismutase (SOD) catalyzes the disproportionation of superoxide (O2• −) into H2O2 and O2(g) by toggling through different oxidation states of a first-row transition metal ion at its active site. Ni-containing SODs (NiSODs) are a distinct class of this family of metalloenzymes due to the unusual coordination sphere that is comprised of mixed N/S-ligands from peptide-N and cysteine-S donor atoms. A central goal of our research is to understand the factors that govern reactive oxygen species (ROS) stability of the Ni–S(Cys) bond in NiSOD utilizing a synthetic model approach. In light of the reactivity of metal-coordinated thiolates to ROS, several hypotheses have been proffered and include the coordination of His1-Nδ to the Ni(II) and Ni(III) forms of NiSOD, as well as hydrogen bonding or full protonation of a coordinated S(Cys). In this work, we present NiSOD analogues of the general formula [Ni(N2S)(SR′)]−, providing a variable location (SR′ = aryl thiolate) in the N2S2 basal plane coordination sphere where we have introduced o-amino and/or electron-withdrawing groups to intercept an oxidized Ni species. The synthesis, structure, and properties of the NiSOD model complexes (Et4N)[Ni(nmp)(SPh-o-NH2)] (2), (Et4N)[Ni(nmp)(SPh-o-NH2-p-CF3)] (3), (Et4N)[Ni(nmp)(SPh-p-NH2)] (4), and (Et4N)[Ni(nmp)(SPh-p-CF3)] (5) (nmp2− = dianion of N-(2-mercaptoethyl)picolinamide) are reported. NiSOD model complexes with amino groups positioned ortho to the aryl-S in SR′ (2 and 3) afford oxidized species (2ox and 3ox) that are best described as a resonance hybrid between Ni(III)-SR and Ni(II)-•SR based on ultraviolet–visible (UV-vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectroscopies, as well as density functional theory (DFT) calculations. The results presented here, demonstrating the high percentage of S(3p) character in the highest occupied molecular orbital (HOMO) of the four-coordinate reduced form of NiSOD (NiSODred), suggest that the transition from NiSODred to the five-coordinate oxidized form of NiSOD (NiSODox) may go through a four-coordinate Ni-•S(Cys) (NiSODox-Hisoff) that is stabilized by coordination to Ni(II).

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“…(ii) Thiolate donors are present in the coordination sphere of metal ions in active sites of metalloproteins [16]; e.g, Fe(II) in peptide deformylase [17], Co (II) in the active site of nitrile hydratase [18], [NiFe]-hydrogenase [19] and metallothioneins containing Zn, Hg, Cd, and Cu [20]. (iii) In the application of certain metalethiolates in medicine, such as Au(I)-thiolates for the treatment of arthritis and triphenylphosphinegold(I) compounds as antitumor agents [21].…”

Section: Introductionmentioning

confidence: 99%

In vivo and in vitro evaluation of highly specific thiolate carrier group copper(II) and zinc(II) complexes on Ehrlich ascites carcinoma tumor model

Raman¹,

Jeyamurugan²,

Senthilkumar

et al. 2010

European Journal of Medicinal Chemistry

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Synthesis and Sulfur Oxygenation of a (N₃S)Ni Complex Related to Nickel-Containing Superoxide Dismutase

Cited by 39 publications

References 29 publications

Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N₂S₂ Synthetic Models of NiSOD

In vivo and in vitro evaluation of highly specific thiolate carrier group copper(II) and zinc(II) complexes on Ehrlich ascites carcinoma tumor model

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Synthesis and Sulfur Oxygenation of a (N3S)Ni Complex Related to Nickel-Containing Superoxide Dismutase

Cited by 39 publications

References 29 publications

Bisamidate and Mixed Amine/Amidate NiN2S2 Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Bisamidate and Mixed Amine/Amidate NiN2S2 Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N2S2 Synthetic Models of NiSOD

In vivo and in vitro evaluation of highly specific thiolate carrier group copper(II) and zinc(II) complexes on Ehrlich ascites carcinoma tumor model

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Product

Resources

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Synthesis and Sulfur Oxygenation of a (N₃S)Ni Complex Related to Nickel-Containing Superoxide Dismutase

Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Bisamidate and Mixed Amine/Amidate NiN₂S₂ Complexes as Models for Nickel-Containing Acetyl Coenzyme A Synthase and Superoxide Dismutase: An Experimental and Computational Study

Accessing Ni(III)-Thiolate Versus Ni(II)-Thiyl Bonding in a Family of Ni–N₂S₂ Synthetic Models of NiSOD